With the prosperous development of modern technologies, novel information products are introduced for satisfying people's various needs. Compared with conventional displays, liquid crystal displays (LCDs) have the advantages of light and compact size, low radiation, and low power consumption. Thereby, current conventional displays in the market have being replaced by LCDs gradually, making LCDs as a mainstream in the display market. No matter which type of LCDs, a driving circuit is required for driving the LCD panel. For a thin-film transistor (TFT) panel, a bidirectional scanning driving circuit is used for controlling if the pixel structure of the TFT receives the data signal provided by the data driving circuit. Thereby, the pixel electrode of the pixel structure can have the voltage corresponding to the data signal, and thus forming the electric field between the common electrode and the pixel electrode for driving the liquid crystals therebetween to rotate. In addition, the rotating angle of the liquid crystals can be adjusted by varying the intensity of the electric field. Because the bidirectional scanning driving circuit outputs scan signals to the gates of the TFTs for driving, the bidirectional scanning driving circuit can also be named as a gate driving circuit.
A conventional TFT-LCD panel is formed by attaching a TFT panel glass to a color filter glass and filling the gap therebetween with liquid crystal molecules. In order to reduce the number of devices as well as lowering the manufacturing cost, the trend is to fabricate the driving circuit structure on the display panel directly in recent years. For example, the gate on array (GOA) technology is to integrate the scanning driving circuit on the liquid crystal panel. This novel mass-production technology performs the color-filter process after completing the TFT array on the TFT panel glass. This technology can improve the aperture ratio of pixels and thus enhancing the brightness of the panel.
The scanning driving circuit is required to respond rapidly and have light and compact designs for LCD panels. In addition, for supporting bidirectional scanning, the influence among devices in the circuit should be reduced and the interference among signals should be minimized as well. Thereby, the layout of the control circuit for bidirectional scanning in the scanning driving circuit need to be simplified. The noise during charging and discharging should be canceled too.
Accordingly, the present invention provides a bidirectional scanning driving circuit, which simplifies the charging and discharging mechanisms and thus reducing the number of transistors required for bidirectional scanning. The present invention can also be applied to the GOA technology for disposing the driving circuit on a thin panel.